Cr-resistant rhizo- and endophytic bacteria associated with Prosopis juliflora and their potential as phytoremediation enhancing agents in metal-degraded soils

Abstract

Prosopis juliflora is characterized by distinct and profuse growth even in nutritionally poor soil and environmentally stressed conditions and is believed to harbor some novel heavy metal-resistant bacteria in the rhizosphere and endosphere. This study was performed to isolate and characterize Cr-resistant bacteria from the rhizosphere and endosphere of P. juliflora growing on the tannery effluent contaminated soil. A total of 5 and 21 bacterial strains were isolated from the rhizosphere and endosphere, respectively, and were shown to tolerate Cr up to 3000 mg l−1. These isolates also exhibited tolerance to other toxic heavy metals such as, Cd, Cu, Pb, and Zn, and high concentration (174 g l−1) of NaCl. Moreover, most of the isolated bacterial strains showed one or more plant growth-promoting activities. The phylogenetic analysis of the 16S rRNA gene showed that the predominant species included Bacillus, Staphylococcus and Aerococcus. As far as we know, this is the first report analyzing rhizo- and endophytic bacterial communities associated with P. juliflora growing on the tannery effluent contaminated soil. The inoculation of three isolates to ryegrass (Lolium multiflorum L.) improved plant growth and heavy metal removal from the tannery effluent contaminated soil suggesting that these bacteria could enhance the establishment of the plant in contaminated soil and also improve the efficiency of phytoremediation of heavy metal-degraded soils.

The Oxidative Stress Response of Mirabilis jalapa to Exhausted Engine Oil (EEO) during Phytoremediation

“…The finding is further confirmed with enzymatic assays indicating the presence of high reactive oxygen species. Finally, the study confirms the toxic nature of EEO, and the results reflect that the plant is least suitable for phytoremediation of EEO but, in future, may be considered with improved phytotechnologies, i.e., a plant-bacteria partnership (rhizobacteria and endophytic bacteria) [12,39,52].…”

“…Recently, phytoremediation has been proven to be one of the best and most cost-effective technologies for restoring the contaminated environment [12][13]. However, the overall success of phytoremediation has remained limited in several ways [14].…”

Plant–bacteria partnerships for the remediation of persistent organic pollutants

“…These synergistic relationships between plants and plantassociated bacterial communities in rhizosphere and/or endosphere have been widely investigated (Compant et al 2010;Fahad et al 2015;Khan et al 2013a). Recently, the combined use of plants and bacteria has been exploited to enhance the phytoremediation of soil and water contaminated with different organic pollutants (Afzal et al 2014b;Arslan et al 2014;Khan et al 2013b;Shehzadi et al 2014). Similarly, several studies were performed to explore the potential of plant-bacteria partnership for the remediation of POPscontaminated soil and water (Aken et al 2009;BecerraCastro et al 2013;Jha and Jha 2015;Jha et al 2014).…”

Floating Wetlands: A Sustainable Tool for Wastewater Treatment

“…The pollutant degradation by endophytic bacteria is not limited to organic contaminants only but can be equally exploited in remediation of potentially toxic metal(s)/element(s). For example, application of endophytic bacteria, previously isolated from Prosopis juliflora grown in soil contaminated with tannery effluent with a high concentration of potentially toxic metals (Cr, Cd, Pb, Cu, and Zn), expressively enhanced the uptake of Cr in ryegrass . Similarly, uptake of Zn was increased considerably by inoculation of two grass species, Festuca rundinacea and Lolium perenne , by the endophytic bacterial strain Neotyphodium …”